BIG-IP GTM

For the BIG-IP® Global Traffic Manager system to operate effectively, you need to define the components that make up the segments of your network. These components include physical components, such as data centers and servers, as well as logical components, such as wide IPs, addresses, and pools. By defining these components, you essentially build a network map that Global Traffic Manager can use to direct Domain Name System (DNS) traffic to the best available resource.

Data centers are the top level of your physical network setup. You must configure one data center for each physical location in your global network. When you create a data center in Global Traffic Manager, you define the servers (Global Traffic Manager systems, Local Traffic Manager systems, Link Controller systems, hosts, and routers) that reside at that location.

A server is a physical device on which you can configure one or more virtual servers. The servers that you define can include both BIG-IP systems and third-party servers, such as Local Traffic Manager systems and systems running Microsoft® Windows® 2000 Server.

A link is a logical representation of a physical device (router) that connects your network to the Internet. You can assign multiple links to each data center by logically attaching links to a collection of servers in order to manage access to your data sources. Configuring links is optional, although they are very useful when determining resource availability.

Servers, excluding Global Traffic Manager systems and Link Controller systems, contain at least one virtual server. A virtual server, in the context of Global Traffic Manager, is a combination of an IP address and a port number that points to a resource that provides access to an application or data source on your network. In the case of host servers, this IP address and port number likely point to the resource itself. With load balancing systems, such as Local Traffic Manager, these virtual servers are often proxies that allow the load balancing server to manage the resource request across a multitude of resources. Virtual servers are the ultimate destination for connection requests.

To communicate with the rest of your network, you must configure Global Traffic Manager so that it can correctly identify the resolution requests for which it is responsible. A listener is an object that monitors the network for DNS queries, and thus is critical for global traffic management. The listener instructs the system to monitor the network traffic destined for a specific IP address.

A pool is a collection of virtual servers that can reside on multiple network servers. When you define the virtual servers to which Global Traffic Manager directs DNS traffic, you combine those virtual servers into pools. You can then configure Global Traffic Manager to direct traffic to a specific virtual server within a pool, using a specific load balancing method.

A distributed application is a collection of one or more wide IPs, data centers, and links that serve as a single application to a web site visitor. A distributed application is the highest-level component that Global Traffic Manager supports. You can configure Global Traffic Manager so that the availability of distributed applications is dependent on a specific data center, link, or server. For example, if the New York data center goes offline, this information causes the wide IP and its corresponding distributed application to become unavailable. Consequently, the system does not send resolution requests to any of the distributed application resources, until the entire application becomes available again.